This example animates the transition between two map projections: starting with an orthographic view of the globe and morphing into a flat equirectangular projection. A red equator line and gray graticule remain visible throughout, highlighting how geographic coordinates shift between the two representations. The animation runs continuously, cycling through the interpolation in both directions. The implementation uses a custom projection function that blends the output coordinates of `d3.geo.orthographic` and `d3.geo.equirectangular`, driven by a transition tween that updates the projection’s alpha parameter and redraws SVG paths rendered by `d3.geo.path`.